OpenCAL - an open-source layerless 3d printer

This project contains the software needed to create your own CAL. It depends on Python 3.x and some system libraries; configuration is stored in utils/config.json.

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Table of Contents

1. Overview
2. Features
3. Installation
4. Configuration
5. Running as a systemd service
6. Usage

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Features

Overview of some features available through the GUI:

1. Print from USB
2. Edit settings
3. Control stepper and LEDs manually
4. Scale the print size %
5. Kill GUI (helps if testing other functions on the Pi)

Overview

This code was written to be run on a Raspberry Pi 5 without any exterior monitor (although one will be needed for setup) and includes software to operate the printer based on the CAL method. All configuration can be tweaked via utils/config.json.

Installation

Prerequisites:

• System packages (listed in apt_requirements.txt)

Steps:

# Clone the repo
git clone https://github.com/computed-axial-lithography/OpenCAL.git
cd OpenCAL

# Install system dependencies
sudo apt update
xargs sudo apt install -y < apt_requirements.txt

# (Optional) create and activate virtual environment
python3 -m venv venv
source venv/bin/activate

# Install Python dependencies
pip install -r requirements.txt

Configuration

Edit utils/config.json to match your hardware setup. For example:

{
  "rotary_encoder": {
    "clk_pin": 5,
    "dt_pin": 6,
    "btn_pin": 19
  },
  "camera": {
    "type": "rpi",
    "index": 0,
    "save_path": "/home/pi/OpenCAL/utils/prints"
  }
}

Running as a systemd service

To have OpenCAL start automatically at boot, register it as a systemd service:

1. Copy the service file

   sudo cp assets/opencal.service /etc/systemd/system/opencal.service

2. Edit the service definition

   sudo nano /etc/systemd/system/opencal.service

   Make sure these fields match your install location and user. For example, if you cloned into /home/pi/OpenCAL and created a venv there, you might have:

   [Unit]
   Description=OpenCAL 3D Printer Service
   After=network.target
   
   [Service]
   User=pi
   WorkingDirectory=/home/pi/OpenCAL
   ExecStart=/home/pi/OpenCAL/venv/bin/python /home/pi/OpenCAL/main.py
   Restart=on-failure

3. Reload, enable, and start

   sudo systemctl daemon-reload
   sudo systemctl enable opencal.service    # start at boot
   sudo systemctl start  opencal.service

4. Verify it’s running

   sudo systemctl status opencal.service
   sudo journalctl -u opencal.service -f

• daemon-reload tells systemd to re-scan unit files.
• enable makes it start on every boot; start fires it now.
• status shows exit codes and recent logs; journalctl -f follows live output so you can spot errors immediately.

Usage

If everything is properly connected and installed, the system can run entirely from the GUI. Expected sequence for printing:

1. Provide .mp4 via USB storage device
2. Navigate to "Print from USB" on the GUI
3. Select .mp4 file for printing
4. Confirm the rotation speed (in rpm) of the resin
5. Start the print or test